Topsides load-out to barge catamaran for float-over installation

ABSTRACT

The present invention provides an improved method and system for load-out of a topsides onto at least two float-over barges without requiring an intermediate transportation barge. The topsides and float-over barges create a catamaran system that can be used to install the topsides to an offshore structure, such as a Spar hull, using a float-over method. The load-out process offers several advantages and can be less time-consuming and less expensive than a typical procedure using the intermediate transportation barge.

CROSS REFERENCE TO RELATED APPLICATIONS

Not applicable.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

REFERENCE TO APPENDIX

Not applicable.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates a method and system of loading out an integrated floating platform topsides from a fabrication or ship yard to a catamaran setup made of two barges for ocean towing and ultimately for a float-over installation onto an offshore structure such as a Spar.

2. Description of the Related Art

Many offshore structures require a topsides to provide support facilities to operate the offshore structures for their intended purpose. For example, a Spar platform is a type of floating oil platform typically used in very deep waters and is among the largest offshore platforms in use. A Spar platform includes a large cylinder or hull supporting a typical rig topsides. The cylinder however does not extend all the way to the seafloor, but instead is moored by a number of mooring lines. Typically, about 90% of the Spar hull is underwater.

Deck or topsides installation has always been a challenge for floating structures, particularly in deep draft floaters like the Spar, which must be installed in relatively deep water. In the past, topsides for most of previous floating structures and particularly, Spar platforms, were installed by heavy lift derrick barges in single or multiple module lifts ranging from about 3000 MT (metric ton) to over 30000 MT. There are some disadvantages in a lifted installation, particularly for large topsides requiring multiple module lifts. In traditional efforts, the topsides requires multi-lifting, for example five to seven lifts, to install the whole topsides due to the lifting capacity of available heavy lifting vessels. Such multi-lift increases the costs and time for installing the topsides to the offshore structure.

Recently catamaran float-over systems have been used to install a topsides onto a Spar hull. A float-over method is a concept in which the topsides is loaded onto at least two separated float-over barges to form a catamaran system and transported with the float-over barges to the installation site for the Spar hull. At the installation site, the float-over barges are positioned on both sides of the Spar hull with the Spar hull below the topsides, the elevation is adjusted between the topsides and the Spar hull, as the topsides is installed to the Spar hull. Installation of the topsides to the Spar hull by the float-over method can allow a high proportion of the hook-up and pre-commissioning work to be completed onshore prior to load-out, which can significantly reduce both the duration and cost of the offshore commissioning phase. The float-over installation method allows for the installation of the integrated topsides or production deck on a fixed or floating structure without any heavy lift operation.

However, to install the topsides onto the separated float-over barges, an intermediate single transportation barge is typically used. The topsides is loaded onto the transportation barge, the transportation barge is positioned between the separated float-over barges, the topsides is then transferred to the float-over barges, and the transportation barge removed. These operations are time consuming, because they require transfer of the topsides from the quay to the transportation barge and after loading the topsides to the transportation barge, then to the two barges. Moreover, this procedure needs three barges.

A further challenge is that the stern of the transportation barge generally lacks adequate strength for the reaction load from the topsides during the load-out at the yard and requires special care and procedures to accommodate the load-out. This challenge is partially due to the practice of aligning the narrower transverse dimension (that is, width) of the transportation barge against the dock with the longer longitudinal dimension (that is, length) extending away from the dock. This alignment is desirable so that when the topsides is loaded onto the transportation barge, the topsides extend beyond the width on each side and can be coupled later to the two separated float-over barges. This relatively narrow width further complicates the loading by resulting in limiting the ballast available at any given width of the transportation barge.

There remains then a need for a load-out method and system that will improve the above challenges of current load-out procedures for a topsides float-over installation.

BRIEF SUMMARY OF THE INVENTION

The present invention provides an improved method and system for load-out of a topsides onto at least two float-out barges without requiring an intermediate transportation barge. The topsides and float-over barges creates a catamaran system that can be used to install the topsides to an offshore structure, such as a Spar hull, using a float-over method. The load-out process offers several advantages and can be less time-consuming and less expensive than a typical procedure using the intermediate transportation barge.

Exemplary benefits can include:

-   -   the skid rails on the float-over barges can be part of the barge         grillage structure for the catamaran system, thus saving a         significant amount of steel compared with a load-out in the         traditional direction along the length of the transportation         barge;     -   the float-over barge strength during the load-out can be greater         than a traditional longitudinal load-out for a transportation         barge, because the section modulus and shear area of the         float-over barges in a transverse direction is generally greater         than in a longitudinal direction, which can become increasingly         important as larger and heavier topsides are loaded out;     -   a longitudinal portion of the float-over barge can be used for         increased ballasting for very heavy topsides at a critical         moment when the topsides supports just land on the barge         compared to a potentially insufficient amount of ballast using         the shorter transverse portion of a transportation barge in a         traditional longitudinal load-out;     -   there can be less, if any, need for a synchronized ballasting         between the two float-over barges as is typically required for a         traditional load-out on twin barges in the direction along the         length of the barges; and/or     -   the topsides can experience minimal racking between the two         barges resulting from a more uniform distribution of the         topsides loads on the supports during the load-out operation to         the float-over barges.

The invention discloses a method of loading out a topsides onto at least two float-over barges to create a catamaran system, comprising: positioning a float-over barge in proximity to a loading structure and restraining movement of the barge relative to the loading structure; loading out a first portion of the topsides from the loading structure onto one barge; separating the barge from the loading structure with the portion of the topsides loaded on the barge; loading out the remainder of the topsides from the loading structure onto an other barge, the barges being separated to create the catamaran system for transportation to an installation site for the topsides.

In at least one embodiment, the method includes: positioning a first float-over barge in proximity to the loading structure and restraining movement of the first float-over barge relative to the loading structure; coupling a second float-over barge to the first float-over barge distally from the loading structure; loading out the portion of the topsides onto the first float-over barge; loading out the portion of the topsides off of the first float-over barge and onto the second float-over barge; decoupling the second float-over barge from the first float-over barge; and loading out the remainder of the topsides onto the first float-over barge and allowing the second float-over barge to be separated by a distance from the first float-over barge.

In another embodiment, the method includes: positioning a first float-over barge in proximity to the loading structure and restraining movement of the first float-over barge relative to the loading structure; loading out the portion of the topsides onto the first float-over barge; allowing the first float-over barge to be moved relative to the loading structure; loading out the topsides toward the first float-over barge and allowing the first float-over barge to be separated by a distance from the loading structure; positioning a second float-over barge in proximity to the loading structure and restraining movement of the second float-over barge relative to the loading structure; and loading out the remainder of the topsides from the loading structure onto the second float-over barge separated from the first float-over barge.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1A is a schematic top view of an exemplary load-out system with a topsides ready to be loaded onto proximally disposed float-over barges at a dock.

FIG. 1B is a schematic side view of the load-out system of FIG. 1A.

FIG. 2A is a schematic top view of the load-out system with a portion of the topsides loaded onto a first float-over barge.

FIG. 2B is a schematic side view of the load-out system of FIG. 2A.

FIG. 3A is a schematic top view of the load-out system with the portion of the topsides loaded beyond the first float-over barge and onto a second float-over barge.

FIG. 3B is a schematic side view of the load-out system of FIG. 3A.

FIG. 4A is a schematic top view of the load-out system with the portion of the topsides loaded onto the second float-over barge with the remainder of the topsides loaded onto the first float-over barge.

FIG. 4B is a schematic side view of the load-out system of FIG. 4A.

FIG. 5A is a schematic top view of another exemplary embodiment of the load-out system with a topsides ready to be loaded onto a proximally disposed first float-over barge at a dock.

FIG. 5B is a schematic side view of the load-out system of FIG. 5A.

FIG. 6A is a schematic top view of the load-out system with a portion of the topsides loaded onto the first float-over barge.

FIG. 6B is a schematic side view of the load-out system of FIG. 6A.

FIG. 7A is a schematic top view of the load-out system with the portion of the topsides loaded onto the first float-over barge and the first float-over barge disposed outward from the dock with a second float-over barge positioned to be placed under the topsides.

FIG. 7B is a schematic side view of the load-out system of FIG. 7A.

FIG. 8A is a schematic top view of the load-out system with remainder of the topsides loaded onto the second float-over barge.

FIG. 8B is a schematic side view of the load-out system of FIG. 8A.

DETAILED DESCRIPTION

The Figures described above and the written description of specific structures and functions below are not presented to limit the scope of what Applicants have invented or the scope of the appended claims. Rather, the Figures and written description are provided to teach any person skilled in the art to make and use the inventions for which patent protection is sought. Those skilled in the art will appreciate that not all features of a commercial embodiment of the inventions are described or shown for the sake of clarity and understanding. Persons of skill in this art will also appreciate that the development of an actual commercial embodiment incorporating aspects of the present inventions will require numerous implementation-specific decisions to achieve the developer's ultimate goal for the commercial embodiment. Such implementation-specific decisions may include, and likely are not limited to, compliance with system-related, business-related, government-related and other constraints, which may vary by specific implementation, location and from time to time. While a developer's efforts might be complex and time-consuming in an absolute sense, such efforts would be, nevertheless, a routine undertaking for those of ordinary skill in this art having benefit of this disclosure. It must be understood that the inventions disclosed and taught herein are susceptible to numerous and various modifications and alternative forms. Lastly, the use of a singular term, such as, but not limited to, “a,” is not intended as limiting of the number of items. Also, the use of relational terms, such as, but not limited to, “top,” “bottom,” “left,” “right,” “upper,” “lower,” “down,” “up,” “side,” and the like are used in the written description for clarity in specific reference to the Figures and are not intended to limit the scope of the invention or the appended claims. Where appropriate, elements have been labeled with an “a” or “b” to designate one side of the system or another. When referring generally to such elements, the number without the letter is used. Further, such designations do not limit the number of elements that can be used for that function.

In general, a portion of a topsides is directly loaded out from a loading structure onto a float-over barge without the intermediate transportation barge discussed above, the float-over barge is allowed to move away from loading structure that causes a separation in distance from an other float-over barge positioned proximal to the loading structure, and a remainder of the topsides is loaded out from the loading structure onto the other barge with the barges separated. Thus, the cataman structure is created during the load-out process from the loading structure without the intermediate step and need for the transportation barge. This method differs significantly from the typical process of loading out the topsides to the transportation barge with the topsides extending outward on both sides of the transportation barge, and then positioning the transportation barge between the float-over barges to transfer the topsides to the float-over barges, as discussed in the background section above.

The load-out process can offer several advantages and can be less time-consuming and less expensive than a typical procedure using the intermediate transportation barge. The load-out method of loading the topsides from a loading structure, such as a fabrication yard and dock, onto at least two float-over barges to create a float-over catamaran system can be described in various steps. The Figures illustrate various steps of an exemplary procedure to achieve the load-out of the topsides to the float-over barges. Each figure will be described below.

FIG. 1A is a schematic top view of an exemplary load-out system with a topsides ready to be loaded onto proximally disposed float-over barges at a dock. FIG. 1B is a schematic side view of the load-out system of FIG. 1A. The figures will be described in conjunction with each other.

A load-out system 2 includes a loading structure 4 and at least two float-over barges 12, 14 with ancillary equipment. The loading structure generally will be a fabrication yard having a dock 6 and plurality of skids rails 8. A topsides 10 is generally fabricated at the fabrication yard with supporting structure including grillage 18 a, 18 b (generally grillage 18). The grillage 18 can be coupled to the float-over barges 12, 14 prior to transporting the topsides on the float-over barges (that is, together forming the catamaran system) to the intended place of installing onto a Spar hull or other offshore structure However, it is to be understood that the present invention is not limited to fabrication yards, skid rails, and docks, and can include, for example, offshore loading structures having the capacity to move a topsides or other structure from a relatively stationary facility to the float-over barges to create a catamaran system. Thus, the embodiment will be described using a fabrication yard and dock for exemplary, but nonlimiting, purposes.

In operation, a first float-over barge 12 is brought to the loading structure 4 and positioned in proximity to the loading structure, such as by the dock 6. The first barge 12 is restrained relative to the loading structure 4, such as by mooring with wire ropes, cables, chains, weldments, and other coupling devices. Alternatively, the first barge 12 can be restrained to some intermediate object to which the loading structure 4 can also be restrained, so that the relative motion between the first barge and the loading structure is restrained sufficiently to allow the topsides 10 to be pushed or pulled onto the first barge. In general, the first barge 12 will be restrained along its length rather than its width, so that it is transverse to the movement of the topsides. This orientation differs from typical load-out procedures onto a transportation barge and allows more support for the topsides 10 as it is loaded out to the barge 12. This orientation also allows more separation between the float-over barges 12, 14, when the topsides is loaded out to the barges.

Further, the second barge 14 is coupled with a coupling member 16 to the first barge 12 distal from the loading structure 4, so that the second barge is outward from the dock 6 relative to the first barge. The second barge 14 can be hingeably coupled to the first barge 12. The coupling member 16 can include a solid hinge system that is bendable in response to forces between the float-over barges. The term “hingeable” coupling is used broadly and can include a bendable coupling that can flex and bend as needed or one that is constrained significantly in one plane and flexibly constrained in another plane. For example, a hingeable coupling can include without limitation a plate steel, such as 1 inch (25 mm) thick plate, that relative to the size of the barges forms a bendable solid hinge that can flex as needed for bending movement of the barges relative to each other and/or the topsides. The coupling can occur along the length of the barge at one or more points.

FIG. 2A is a schematic top view of the load-out system with a portion of the topsides loaded onto a first float-over barge. FIG. 2B is a schematic side view of the load-out system of FIG. 2A. The figures will be described in conjunction with each other.

A portion of the topsides 10 containing the grillage 18 a can be pushed or pulled onto the first barge 12, generally along the skid rails 8. A drive mechanism, not shown, but known to those with ordinary skill in the art given the disclosure herein, can include a movable hydraulic cylinder that can be coupled to the skid rails 8 to push or pull the portion of the topsides onto the barge 12. Alternatively, the drive mechanism can include one or more winches and sheaves disposed at various locations, such as on the barge 12, to pull the topsides toward the barge. The term “drive mechanism” is to be broadly construed to include any motive force adapted to move the topsides. Generally, the portion that is pulled onto the first barge will include the grillage 18 a. The topsides 10 is thus skidded or otherwise moved from the skid rails 8 onto the barge 12 transversely to the barge length, while adjusting ballast on the barge 12 to maintain an advantageous alignment of the skid rails with the barge 12. The barges remain in relative fixed position to each other and to the loading structure due to the restrained movement between the first barge and the loading structure and between the barges.

FIG. 3A is a schematic top view of the load-out system with the portion of the topsides loaded beyond the first float-over barge and onto a second float-over barge. FIG. 3B is a schematic side view of the load-out system of FIG. 3A. The figures will be described in conjunction with each other.

The topsides 10 is skidded or otherwise moved onto the float-over barges 12, 14. Specifically, the portion of the topsides 10 that moved onto the first barge 12 is progressively moved onto the second barge 14 while the second barge 14 is coupled to the first barge 12 with the coupling member 16. Thus, the grillage 18 a is moved from the first barge 12 onto the second barge 14. Generally, the grillage 18 a will be coupled to the barge. One or more sea fastening members (not shown) can be coupled between the barge 14 and the topsides 10 including the grillage 18 a for use during transportation of the topsides to the site of the offshore structure to which the topsides is to be installed.

FIG. 4A is a schematic top view of the load-out system with the portion of the topsides loaded onto the second float-over barge with the remainder of the topsides loaded onto the first float-over barge. FIG. 4B is a schematic side view of the load-out system of FIG. 4A. The figures will be described in conjunction with each other.

The coupling member 16 between the barges 12, 14 is removed, severed, or otherwise decoupled. Then, the second barge 14 can move relative to the first barge 12 and be separated from the first barge. The topsides 10 is further moved from the loading structure 4 onto the first barge 12 that is still restrained with the loading structure 4. However, the second barge 14 can move outward from the first barge 12 as the topsides 10 is moved. A separation occurs between the first barge 12 and second barge 14, creating the catamaran system. The topsides is continued to be moved until the grillage 18 b is disposed on the first barge 12. The grillage 18 b can be coupled to the first barge 12. Thus, the topsides 10 is coupled to the two separate float-over barges 12, 14, so that a center of the topsides is disposed therebetween. Further, the topsides can be hingeably coupled to the barges, the grillage system, or a combination thereof to allow for movement during the load-out, transportation to the installation site, and installation onto the particular offshore structure for which the topsides is intended.

The first barge is decoupled or otherwise unrestrained from the loading structure and allowed to move relative to the loading structure and in conjunction with the second barge. The catamaran system of the topsides 10 and the two barges 12, 14 can be transported, such as by towing, to an offshore structure to install the topsides.

FIG. 5A is a schematic top view of another exemplary embodiment of the load-out system with a topsides ready to be loaded onto a proximally disposed first float-over barge at a dock. FIG. 5B is a schematic side view of the load-out system of FIG. 5A. The figures will be described in conjunction with each other.

The elements are similarly labeled as above in FIGS. 1A-4B. The load-out system 2 includes a loading structure 4 and at least two float-over barges 12, 14 with ancillary equipment. The loading structure generally will be a fabrication yard having a dock 6 and plurality of skids rails 8, although other loading structures can be used. The topsides 10 is generally fabricated at the fabrication yard with supporting structure including grillage 18 a, 18 b (generally grillage 18).

This embodiment uses similar concepts of loading one barge with the topsides from the loading structure, separating the barges, and loading out the remainder of the topsides from the loading structure onto an other barge with the barges separated. However, the sequence of positioning the barges in proximity to the loading structure varies from the first embodiment described in FIGS. 1A-4B as follows.

In operation, a first float-over barge 12 is positioned proximal to the loading structure 4, such as by the dock 6. The barge 12 is restrained from movement relative to the loading structure by wire ropes, cables, and/or chains or other coupling devices, including through intermediate members. As described above, in general, the barge 12 will be restrained along its length, so that it is transverse to the movement of the topsides. A second float-over barge 14 can be positioned distally from the topsides and optionally aligned with the first float-over barge 12 in the longitudinal direction, so that the second barge can be readily substituted in place of the first barge, as described below.

FIG. 6A is a schematic top view of the load-out system with a portion of the topsides loaded onto the first float-over barge. FIG. 6B is a schematic side view of the load-out system of FIG. 6A. The figures will be described in conjunction with each other.

A portion of the topsides 10 containing the grillage 18 a can be pushed or pulled onto the first barge 12, generally along the skid rails 8. A drive mechanism, not shown, but known to those with ordinary skill in the art given the disclosure herein, can include a movable hydraulic cylinder that can be coupled to the skid rails 8 to push or pull the portion of the topsides onto the barge 12. Alternatively, the drive mechanism can include one or more winches and sheaves disposed at various locations, such as on the barge 12, to pull the topsides toward the barge. Generally, the portion that is pulled onto the first barge will include the grillage 18 a. The topsides 10 is thus skidded or otherwise moved from the skid rails 8 onto the barge 12 transversely to the barge length while adjusting ballast on the barge 12 to maintain an advantageous alignment of the skid rails with the barge 12.

FIG. 7A is a schematic top view of the load-out system with the portion of the topsides loaded onto the first float-over barge and the first float-over barge disposed outward from the dock with a second float-over barge positioned to be placed under the topsides. FIG. 7B is a schematic side view of the load-out system of FIG. 7A. The figures will be described in conjunction with each other.

While held by a mooring system in the direction normal to the load-out direction, the first barge 12 is allowed to move away from the loading structure 4 by decoupling or unrestraining the barge from the loading structure and the dock 6, if present. The topsides 10 is further moved from the loading structure 4 toward the first barge 12 to cause a separation distance between the loading structure 4 and the first barge 12.

While the first barge 12 is separated from the loading structure and a remainder of the topsides 10 is on the loading structure, the second float-over barge 14 can be moved into a proximal position to the topsides and the loading structure. In general, the second barge 14 will be substituted in place of the prior location of the first barge 12, before the first barge was allowed to be separated from the loading structure 4.

FIG. 8A is a schematic top view of the load-out system with remainder of the topsides loaded onto the second float-over barge. FIG. 8B is a schematic side view of the load-out system of FIG. 8A. The figures will be described in conjunction with each other.

The topsides is continued to be moved until the grillage 18 b is disposed on the second barge 14. The grillage 18 b can be coupled to the second barge 12. Thus, the topsides 10 is coupled to the two separate float-over barges 12, 14, so that a center of the topsides is disposed therebetween with the barges 12, 14 being separated by a distance suitable for a float-over installation of the topsides. Further, the topsides can be hingeably coupled to the barges, the grillage system, or a combination thereof to allow for movement during the load-out, transportation to the installation site, and installation onto the particular offshore structure for which the topsides is intended.

While still restrained in its own longitudinal direction by mooring lines, the second barge is decoupled or otherwise unrestrained from the loading structure and allowed to move relative to the loading structure and in conjunction with the first barge. The catamaran system of the topsides 10 and the two barges 12, 14 can be transported, such as by towing, to an offshore structure to install the topsides.

Optionally, ballast can be added, moved, or removed from the barges 12, 14 to preload a force from the barges to the topsides to reduce a sagging bending moment caused by the weight of the topsides, as more fully explained in co-pending U.S. patent application Ser. No. 12/393,617, incorporated herein by reference. The ballast can be added to the barges prior to, during, or after the load-out.

Other and further embodiments utilizing one or more aspects of the inventions described above can be devised without departing from the spirit of Applicant's invention. Further, the various methods and embodiments of the catamaran system can be included in combination with each other to produce variations of the disclosed methods and embodiments. Discussion of singular elements can include plural elements and vice-versa. References to at least one item followed by a reference to the item may include one or more items. Also, various aspects of the embodiments could be used in conjunction with each other to accomplish the understood goals of the disclosure. Unless the context requires otherwise, the word “comprise” or variations such as “comprises” or “comprising,” should be understood to imply the inclusion of at least the stated element or step or group of elements or steps or equivalents thereof, and not the exclusion of a greater numerical quantity or any other element or step or group of elements or steps or equivalents thereof. The device or system may be used in a number of directions and orientations. The term “coupled,” “coupling,” “coupler,” and like terms are used broadly herein and may include any method or device for securing, binding, bonding, fastening, attaching, joining, inserting therein, forming thereon or therein, communicating, or otherwise associating, for example, mechanically, magnetically, electrically, chemically, directly or indirectly with intermediate elements, one or more pieces of members together and may further include without limitation integrally forming one functional member with another in a unity fashion. The coupling may occur in any direction, including rotationally.

The order of steps can occur in a variety of sequences unless otherwise specifically limited. The various steps described herein can be combined with other steps, interlineated with the stated steps, and/or split into multiple steps. Similarly, elements have been described functionally and can be embodied as separate components or can be combined into components having multiple functions.

The inventions have been described in the context of preferred and other embodiments and not every embodiment of the invention has been described. Obvious modifications and alterations to the described embodiments are available to those of ordinary skill in the art. The disclosed and undisclosed embodiments are not intended to limit or restrict the scope or applicability of the invention conceived of by the Applicants, but rather, in conformity with the patent laws, Applicants intend to fully protect all such modifications and improvements that come within the scope or range of equivalent of the following claims. 

1. A method of loading out a topsides onto at least two float-over barges to create a catamaran system, comprising: positioning a float-over barge in proximity to a loading structure and restraining movement of the barge relative to the loading structure; loading out a first portion of the topsides from the loading structure onto one barge; separating the barge from the loading structure with the portion of the topsides loaded on the barge; loading out the remainder of the topsides from the loading structure onto an other barge, the barges being separated to create the catamaran system for transportation to an installation site for the topsides.
 2. The method of claim 1, comprising: positioning a first float-over barge in proximity to the loading structure and restraining movement of the first float-over barge relative to the loading structure; coupling a second float-over barge to the first float-over barge distally from the loading structure; loading out the portion of the topsides onto the first float-over barge; loading out the portion of the topsides off of the first float-over barge and onto the second float-over barge; decoupling the second float-over barge from the first float-over barge; and loading out the remainder of the topsides onto the first float-over barge and allowing the second float-over barge to be separated by a distance from the first float-over barge.
 3. The method of claim 2, further comprising transporting the float-over barges and topsides to an offshore structure to install the topsides.
 4. The method of claim 2, further comprising disposing a center of the topsides laterally between the float-over barges.
 5. The method of claim 2, wherein coupling the second float-over barge to the first float-over barge further comprises hingeably coupling the float-over barges together.
 6. The method of claim 2, further comprising hingeably coupling the topsides to the float-over barges.
 7. The method of claim 1, comprising: positioning a first float-over barge in proximity to the loading structure and restraining movement of the first float-over barge relative to the loading structure; loading out the portion of the topsides onto the first float-over barge; allowing the first float-over barge to be move relative to the loading structure; loading out the topsides toward the first float-over barge and allowing the first float-over barge to be separated by a distance from the loading structure; positioning a second float-over barge in proximity to the loading structure and restraining movement of the second float-over barge relative to the loading structure; and loading out the remainder of the topsides from the loading structure onto the second float-over barge separated from the first float-over barge.
 8. The method of claim 7, further comprising transporting the float-over barges and topsides to an offshore structure to install the topsides.
 9. The method of claim 7, further comprising disposing a center of the topsides laterally between the float-over barges. 